1. Field of the Invention
The present invention relates generally to fans for moving air. More specifically, the present invention concerns a high performance tubeaxial fan that provides increased efficiency and reduced noise levels relative to prior art tubeaxial fans.
2. Discussion of Prior Art
Fans are used in a variety of household and industrial applications to force air into and/or out of certain environments. For example, many industrial settings utilize ventilation systems that incorporate one or more fans to provide clean air and/or to exhaust polluted air from various work locations. The optimum fan for a particular application will have certain performance criteria required by the application (e.g., flow volume requirements, pressure differentials, etc.).
Tubeaxial fans are known in the art and are particularly suited for applications requiring the movement of large amounts of air with only relatively small pressure differentials (e.g., spray booths, cleaning tanks, mixing rooms, etc.). However, these prior art tubeaxial fans, while effective, have several non-optimizing limitations. For example, prior art tubeaxial fans have a relatively high noise level during operation. High noise levels are undesirable because many applications where tubeaxial fans are utilized involve settings where humans live or work. Furthermore, prior art tubeaxial fans have a relatively low efficiency. Low efficiency is undesirable because many applications where tubeaxial fans are utilized involve extended periods of continuous or repeated fan use.
The present invention provides an improved tubeaxial fan that does not suffer from the limitations of the prior art tubeaxial fans as set forth above. The inventive fan provides a high performance tubeaxial fan that combines both reduced noise levels and improved efficiency relative to the prior art tubeaxial fans.
The present invention concerns a tubeaxial fan assembly that broadly includes a tubular propeller housing, a propeller rotatably supported in the housing for rotation about a rotational axis, and a drive assembly operable to rotate the propeller. The propeller includes a central hub and a plurality of blades fixed relative to the hub to project radially therefrom. Each of the blades presents a root adjacent the hub and a tip spaced radially outward from the root. Each of the tips is spaced from the rotational axis a tip radius. Each of the blades presents a chord length that is smaller at the root and tip relative to a maximum chord length location spaced between the root and tip. Each of the blades presents a stagger angle that is relatively greater at the tip than at the root. Each of the blades presents a camber height that is smaller at the root and tip relative to a maximum camber height location spaced between the root. The drive assembly includes a shaft that is fixed relative to the hub and extends at least generally along the rotational axis, a bearing that rotatably supports the shaft, and a protective bearing cover that encases the bearing and at least a portion of the shaft. The drive assembly also includes an endless element that is drivingly connected to the shaft and extends outside the housing, and an element cover that is located within the housing and at least substantially encloses the element within the housing. The bearing cover presents a wall extending along, and generally parallel to, the at least a portion of the shaft in a covering relationship to the bearing and the at least a portion of the shaft. The wall is spaced from the element cover so that the at least a portion of the shaft is located between the element cover and the wall. The wall is spaced from the rotational axis a cover dimension that is less than about one-third the tip radius. The element cover presents opposite upstream and downstream ends spaced along the rotational axis and tapers toward the upstream and downstream ends.